This invention relates to an Fe-based soft magnetic alloy utilized particularly suitable for producing such as a magnetic core.
Conventionally, crystalline materials such as Permalloy and Ferrite have been used as a magnetic core material utilized for such as a switching regulator operated in a high frequency range.
However, the Permalloy has a low specific resistance, and consequently, the iron loss thereof increases in a high frequency. On the other hand, the Ferrite has a low iron loss in a high frequency, but the magnetic flux density thereof is as low as 5000 Gauss at most, and consequently, the iron loss thereof increases close to a saturation point when used at a high operating magnetic flux density.
Recently miniaturization of sizes is desired for a power transformer used at a switching regulator and for a choke coil, a common mode choke coil and the like used at a transformer operated in a high frequency.
For the miniaturization, an increase of an operating magnetic flux density is vital and, in this regard, a decrease of an iron loss of the Ferrite becomes the key issue for the practical use thereof.
In these days, an amorphous magnetic alloy having no grain (crystalline particle) has attracted considerable attention as a candidate for dissolving the above mentioned problems, because the amorphous magnetic alloy possesses excellent soft magnetic characteristics such as a high magnetic permeability and a low coercive force and, in this regard, is sometimes utilized in actual use.
The amorphous magnetic alloy contains Iron (Fe), Cobalt (Co), Nickel (Ni) as basic components, and Phosphorus (P), Carbon (C), Boron (B), Silicon (Si), Aluminium (Al), Germanium (Ge) are supplementally added thereto as elements for achieving amorphous state (Metalloid). However, the amorphous magnetic alloy does not always shows a low iron loss in every frequency and low material cost.
For example, an Fe-based amorphous magnetic alloy is economical and exhibits a very low iron loss almost one-fourth as great as Silicon steel in a low frequency in the range of 50-60 Hz but, in a high frequency over the range of 10 KHz, the Fe-based amorphous magnetic alloy shows such a considerably high iron loss which can hardly be suitable for an equipment use such as a switching regulator used in a high frequency.
For improving this drawback, a fraction of the Fe of an Fe-based amorphous magnetic alloy is replaced by a non magnetic metal such as Niobium (Nb), Molybdenum (Mo) and Chromium (Cr) in order to lower a magnetostriction for decreasing an iron loss and for increasing a high magnetic permeability thereof. However, in case of a magnetic core formed by a resin mold, some compressive stresses are imposed on the magnetic core because of a curing shrinkage of the resin, so that the inferiority of magnetic characteristics becomes relatively remarkable as time passing. For this reason an Fe-based amorphous magnetic alloy has not reached at sufficient characteristics to suit to the practical use as a soft magnetic material in a high frequency.
On the other hand, a Co-based amorphous magnetic alloy is put into actual use as a magnetic parts of electric equipment such as a saturable reactor because of the low iron loss and the high squareness ratio of magnetic characteristics thereof in a high frequency. However, the material cost thereof is comparatively high. As stated above, an Fe-based amorphous alloy is an economical soft magnetic material but has a restriction in actual use thereof in a high frequency because of a relatively large magnetostriction and an inferiority to a Co-based amorphous alloy in aspect of an iron loss and a magnetic permeability.
Although a Co-based amorphous alloy has superior magnetic characteristics, the Co-based amorphous alloy has a disadvantage of the high material cost thereof.